Suppose meiosis occurs in a meiocyte in an anther of a plant in which 2n=6. What proportion of pollen grains will receive a complete set of centromeres from the plant's maternal parent? (Think of the maternal centromeres as being blue and the paternal ones as being red).
Meiosis produces cells which have half the number of chromosomes as the parents.
If we start with a cell that has 2n=6, we are really starting with a cell that has a "duplicated" 2n=6. Each one of its chromosomes is a duplicated chromosome with sister chromatids. In other words, there are four copies of each gene in the cell. After the first meiotic division, homologous chromosomes separate, not sister chromatids. Therefore, after meiosis I, each daughter cell now has n=3, but each chromosome is still duplicated. There are two copies of each gene in these cells ...